The fusion of metallic nickel with sodium dioxide was reported in 1896 by W. L. Dudley in 18 J. Am. Chem Soc. 901. Dudley fused sodium dioxide in a nickel crucible with nickel metal at a cherry-red heat, about 700.degree.-800.degree.C, for about one hour. After cooling, the contents were submerged in water. The formed brown crystals were then washed to remove alkali. The crystals were then dried at 110.degree.C. The crystals were analyzed and believed to be the dihydrate Ni.sub.3 O.sub.4 . 2H.sub.2 O, with 0.7 wt% cobalt as an impurity. A cobaltocobaltic dihydrate Co.sub.3 O.sub.4 . 2H.sub.2 O is also described as obtained by exposing to moist air Co.sub.3 O.sub.4, prepared by heating cobalt carbonate. These materials were believed to be new compounds but no active battery material or electrochemical use was suggested.
Presently used methods for the preparation of nickel active battery material involve chemical precipitation or electrochemical precipitation of divalent nickel (II) hydroxide, as taught for example by Feduska et. al. in U.S. Pat. No. 3,579,385 and Hardman in U.S. Pat. No. 3,600,227. Faber, in U.S. Pat. No. 3,436,267, converted directly to trivalent Ni (III) hydroxide battery material, by 100% oxidation of finely divided Ni (II) hydroxide powder in a gas stream containing ozone. He then pasted this material into an electrode plaque.
The usual procedure in making a battery plate involves loading the divalent nickel (II) hydroxide into a porous plaque, with oxidation of the material in the plaque to a form of trivalent nickel (III) hydroxide. This is accomplished by electrochemical charging and discharging "formation" of the loaded plaque in an alkaline electrolyte, prior to introduction of the plaque into a battery.
Ozone treatment involves a complex process using expensive equipment. Electro-precipitation processes are also costly and represent a disproportionate share of the raw materials expense in iron-nickel batteries, while chemical precipitation methods result in gelatinous materials which are difficult to load into a conducting matrix.
All three of these methods involve initial production of nickel hydroxide. Chemical precipitation means high cost starting materials, precipitation, filtering, washing, drying, grinding, etc., all of which make the cost of the final electrode powder high. Electro-precipitation and ozone treatment involve major capital expenditures for hardware in addition to high costs for starting materials.
With the increasing importance of improved batteries as a clean power source, especially in the transportation area, there is a need for improved active materials, that will provide capacities closer to the theoretical limit than heretofore possible. To make these batteries commercially feasible, the costs of active material manufacture must be drastically reduced. What is needed then is a method of making inexpensive highly active materials.